1. Field of the Invention
This invention relates generally to a turbo system used on a combustion-type engine for increasing the power of such an engine, and more specifically, to a turbo system and method of installing a turbo system on a vehicle, water craft, or other combustion-type, engine driven device or vehicle.
2. Background of the Invention
Turbo systems in the automotive industry have been available for several decades. During that period of time, there have been many advances in such turbo systems including ways to increase their efficiency and increase their effect on engine horse power.
A turbocharger utilizes the energy in the exhaust gases of an internal combustion engine to drive an impeller. The turbocharger consists of two impellers on opposite sides of a common shaft. One impeller in fluid communication with the exhaust gases of the engine functions as a fluid motor. The interaction of the flow and expansion of exhaust gases passing through the turbine impeller causes rotation of the turbine impeller and thus rotation of the shaft of the turbocharger. The other impeller, or compressor impeller, acts as an air pump to draw in ambient air, increase its velocity and density and discharge it to a pressure chamber where the energy is now higher than the energy in the ambient air. This higher pressure air is then fed into the air intake of the engine to increase the air flow into the engine.
Typically, an oil line is attached to the turbocharger housing, and feeds into bearings along the central or intermediate portion of the common shaft. This oil is then gravity fed through a lower portion of the housing into a second line, which feeds into an oil reservoir, such as the oil pan of a vehicle. As such, there is a continuous flow of lubricating oil to the bearings of the turbocharger to lubricate and thus extend the life of the bearings of the turbocharger. The oil is allowed to drain through an outlet of the turbocharger bearing housing back into the engine crankcase, which under non-accelerating conditions (e.g., when turbo shaft rpms are relatively low) may have close to atmospheric pressure conditions. Under boost conditions (e.g., when turbo shaft rpms may be in excess of 100,000 rpms and heat is being absorbed by the bearings and oil) however, during boost, crankcase pressures are substantially increased. This increase in pressure lessens the pressure differential between the inlet and outlet side of the turbocharger bearing housing, which in turn will decrease the flow of oil through the turbocharger.
It is well known that build-up of pressure in the pressure of the oil leaving the turbocharger needs to be avoided. If the oil pressure becomes great enough, some of the oil may enter the seal area immediately adjacent one or both of the impeller wheels and become mixed with the hydraulic pathways associated with the impeller wheels. Any pressure build up or restriction of the oil outlet consequently restricts inlet oil flow and results in a lower volume of lubrication across the turbocharger bearings causing damage to the bearings and shaft of the turbocharger and eventually a turbocharger failure.
In a conventional turbocharger set up, the turbocharger is placed at or near the top of the oiling system which allows gravity to drain substantially all of the oil from the turbocharger and associated fittings, oil inlet and outlet lines and hoses. This conventional turbocharger installation method results in a xe2x80x9cdryxe2x80x9d condition upon engine startup. Thus, the turbocharger can begin spinning at relatively high rpms without adequate lubrication until lubricating oil finally reaches the turbocharger. Spinning the turbocharger without adequate lubrication can cause increased wear of bearings and other components and result in premature failure of the turbocharger.
Because of the well-known problems associated with oil pressure build up inside the turbocharger, there have been attempts in the art to provide various methods of addressing this issue. For example, in U.S. Pat. No. 4,142,608, part of the high-pressure exhaust gas is permitted to escape through a bleed in a seal which is associated with the motor impeller. Thus, according to the invention, the flow of oil is assisted because of the tendency of the bled exhaust gas to carry the exhaust oil in the same direction due to a pressure differential.
Consistent with the advances in turbocharger technology and the known problems associated with any buildup of oil pressure of oil leaving the turbocharger, it is standard practice to mount the turbocharger next to the engine block well above the oil level to facilitate unrestricted gravity draining of oil from the turbocharger back to the oil pan reservoir. In addition, because the turbocharger is connected to the engine exhaust, the turbocharger is commonly mounted directly on or adjacent to the exhaust manifold so as to make the exhaust gas interconnection between the exhaust manifold and the turbocharger more easily connected. Because of the close proximity of the turbocharger to the exhaust manifold at a point where the engine gases are still extremely hot, the turbocharger receives engine gases that are still burning as they enter the turbocharger. Accordingly, the internal temperatures of a turbocharger are typically close to those of the engines combustion chamber. Such heat surely shortens the life of a turbocharger, as heated components tend to wear more rapidly as lubricants are typically less effective at higher temperatures.
Conventional turbocharger installations are quite difficult due to the lack of space under the hood of most modern vehicles. Installing an aftermarket turbocharger system into an already overcrowded engine compartment most often necessitates the relocation of many factory-installed components to make room for the turbocharger system. Such relocation of equipment significantly adds to the expense of conventional turbocharger installations. The addition of all of these extra components and extra plumbing required to mount a traditional turbocharger system under the hood severely overcrowds an already crowded engine compartment making it extremely difficult to do the standard maintenance and any repair work required to keep the vehicle in good condition and greatly increases the labor costs associated with any future maintenance or repairs needed to be performed.
In addition, extreme under-hood temperatures are generated by turbochargers sometimes causing the cooling system of the vehicle to exceed its capabilities and require that a cooling system upgrade be performed as well. Furthermore, these extreme under-hood temperatures can effect various plastic and rubber engine and vehicle components by causing them to fail. To prevent such overheating of auxiliary components near the turbocharger, expensive heat shielding is added around the turbocharger. While protecting auxiliary components surrounding the turbocharger, such shielding compounds the temperature of the turbocharger itself by preventing, to some extent, the dissipation of heat from the turbocharger. In point of fact, turbocharger temperatures can become so extreme during aggressive driving conditions that the turbocharger bearings can be detrimentally affected unless the turbocharger is allowed to cool down for a period of time with the engine idling before the engine is shut off.
Heating air causes air expansion, which creates a xe2x80x9cfalse pressurexe2x80x9d (increase in pressure without an increase in air volume). Horsepower is lost at a ratio of approximately 1 HP per Degree Fahrenheit (within certain limits). In an attempt to combat high charge air temperatures and the consequent horsepower losses which are a result of extreme turbocharger temperatures, most typical turbocharger applications utilize an intercooler mounted in front of the radiator. The intercooler removes excess heat from the intake charge air that comes out of the turbocharger compressor. The intercooled intake charge adds additional power by providing cooler, denser air to the engine. An intercooler, however, causes a restriction in the flow of charge air creating a pressure differential across the intercooler. Accordingly, the compressor needs to make several pounds more boost than actually enters the engine to overcome the pressure drop across the intercooler. Moreover, compressing the air to a higher pressure causes further heating of the already hot air. Thus, the added demands on the turbocharger compressor further increase the operating temperature of the turbocharger.
As with the installation of a turbocharger, the installation of intercooler components is expensive and sometimes difficult to mount because of their size and the limited space available in front of the radiator of modern vehicles. Many times, the only room to mount the intercooler is below the radiator (near the ground. This exposes the expensive and fragile intercooler to damaging road debris that can clog and restrict the flow of the air through the intercooler, reducing its cooling capacity and efficiency.
The present invention of a turbo system overcomes the above-discussed drawbacks of prior art turbo systems to provide a more efficient, easier installing, and less expensive turbo system alternative.
Accordingly, a remotely mountable turbo system is configured for mounting along the exhaust of an internal combustion engine regardless of whether the turbocharger is above, at or below the oil level of the oil reservoir of the engine. The turbo system is comprised of a turbocharger that is coupled to the engine exhaust. More specifically, as with a conventional turbocharger, the exhaust is coupled to the turbocharger so as to drive the turbine impeller of the turbocharger causing rotation of the compressor impeller.
As the compressor impeller spins, outside air is pulled into the compressor and fed to the engine intake, throttle body or carburetor. In order to minimize debris entering the compressor, an air filter is coupled to the air intake of the compressor. In one embodiment, the air filter is located in a position where it will not be exposed to the elements that may otherwise require premature replacement of the air filter once air flow is significantly restricted by the collection of various particles and away from the heat of the engine.
In one embodiment, the oil for the turbocharger is supplied through a high-pressure line from an engine oil pressure supply. The oil is then evacuated from the turbocharger via an oil pump. The oil pump then pumps the oil from the turbocharger back to the oil pan, crankcase or other oil reservoir of the engine.
Remote mounting of the turbocharger of the present invention is to a large extent dependent upon the proper removal of oil from the bearing housing after it passes through the bearings. The pump of the present invention is capable of effectively pumping oil in all operating temperature ranges from the extreme cold of startup in winter to the extreme hot experienced during full boost conditions in the heat of summer. The pump has a near 100% duty cycle so that it can perform effectively during extended driving. The pump is compact, self contained and operable by an integral 12-volt DC motor for easy connection to a vehicle""s 12-volt electrical system. In one embodiment, the oil pump is a 12-volt gear pump.
The oil pump creates a xe2x80x9cvacuumxe2x80x9d or xe2x80x9csuctionxe2x80x9d effect on the outlet side of the turbocharger. Thus, a pressure differential is created between the inlet and outlet sides of the turbocharger bearing housing. As such, a more free exchange or flow of oil is created (compared to the gravity fed systems of the prior art) through the turbocharger bearings resulting in more efficient lubrication of the turbocharger bearings.
Use of an electric oil pump to pump oil from the turbocharger outlet to the crankcase of the engine (for example), allows for installation of a turbocharger system in accordance with the present invention on engines that may not have an engine oiling system capable of handling a turbocharger or no oiling system at all. For example, some two stroke engines use oil mixed with the fuel to lubricate the engine.
In an alternative embodiment, use of an oil pump of the present invention on such engines is incorporated by also including a separate oil sump and oil cooler that will provide the turbocharger with its own self-contained oiling system. Thus, the turbocharger of the present invention may be installed on virtually any gas or diesel powered engine, even those where conventional turbo systems are not suitable or even possible.
In one embodiment, the turbocharger is mounted at the location of the muffler of a conventional automobile. Because of the noise reducing effects of the turbocharger, the muffler of the vehicle may be completely replaced with the turbocharger. In the alternative, a smaller supplemental muffler may be coupled to the exhaust port of the turbine to further reduce exhaust noise. By mounting the turbocharger at the location of the stock muffler, modifications within the engine compartment that may otherwise be required to create space for an engine-mounted turbocharger can be avoided. In most cases, the turbocharger installation of the present invention results in less crowding of the engine compartment than the stock vehicle before the installation, creating more access room to facilitate and lower the costs of maintenance or repair work required to be performed on the vehicle. Furthermore, the space for the stock muffler is generally sufficient space for mounting of the turbocharger once the stock muffler is removed.
When mounting the turbocharger at the location of the stock muffler, for example, the oil line into the turbocharger will most likely be below the oil level of the engine. As such, a check valve is installed in the oil feed line. For example, a 5 psi check valve will ensure that the engine is running to prevent engine oil from draining into the turbocharger when the engine is not running. When the engine is started, the oil feed line will pressurize and cause the check valve to open as exhaust flows into the intake turbine. The use of the check valve to maintain oil between the engines oil pump and the turbocharger creates a xe2x80x9cwetxe2x80x9d condition upon startup which quickly lubricates the turbocharger upon engine startup. In a conventional turbocharger installation, the turbocharger is placed at the xe2x80x9ctopxe2x80x9d of the oil system which causes gravity to evacuate the lubricating oil from the turbocharger, fittings, lines, and hoses when the engine is turned off. Upon engine startup, prior art turbo systems can run for a period time in a xe2x80x9cdryxe2x80x9d state until oil is circulated back to the turbocharger. Thus, the turbocharger turbines and shaft can be spinning at high rpms without proper lubrication effecting bearing and shaft life of the turbocharger.
In another embodiment, a wastegate valve is coupled to the exhaust prior to entry into the turbine. The wastegate opens with boost pressure to bypass exhaust around the turbocharger to slow the turbine impeller and thus control boost. Without the wastegate, the compounding effect of the exhaust with boost could cause the boost pressure to rise exponentially with engine rpm. Smaller turbine housings produce adequate boost at lower rpms but produce uncontrollably high boost at high rpms. Larger turbine housings produce little or no boost at lower rpms, but efficient boost at higher rpms. The wastegate allows use of smaller turbine housings to obtain low rpm boost and power while controlling the boost limit as rpm increases to prevent the compounding effect that could otherwise occur as engine rpm increases.
By mounting the turbocharger away from the exhaust manifold of the engine, the temperature of the exhaust can be significantly decreased before it enters the turbocharger. Heat is a major drawback of conventional turbocharger systems. The restriction of the exhaust flow causes excess heat to build up in the exhaust system. Since the turbocharger turbine and compressor are integrally connected, much of this excess exhaust heat is transferred from the turbine side to the compressor side and consequently into the compressor intake air. Such heat transfer significantly reduces the efficiency of the turbocharger.
As it is typical to mount turbochargers directly onto the exhaust manifold of the engine, the exhaust entering the turbocharger is extremely hot and often still xe2x80x9cflaming,xe2x80x9d causing extreme turbocharger temperatures. Conversely, mounting the turbocharger at the rear of the vehicle according to the present invention, allows the exhaust heat to dissipate as it flows through the exhaust system which cools down and stabilizes the gases before they enter the turbine. This greatly reduces the turbocharger temperature thereby increasing the consistency of the flow of gases through the turbocharger, and ultimately, the turbocharger performance and efficiency. Furthermore, mounting the turbocharger under the vehicle instead of under the hood where temperatures sometimes exceed 300 degrees Fahrenheit, as is the conventional mounting location, allows a higher volume of cold air to circulate around the turbocharger and related exhaust components to increase the cooling of these components. Such cooler turbocharger temperatures create less stress on the bearings of the turbocharger and related components as well as less heat effects on the engine oil and less heat transfer from the turbine to the compressor, ultimately, producing a cooler charge air.
Because of the ability to mount the turbocharger of the present invention at a location away from the engine at a downstream point along the engine exhaust pipe, the entire system operates at cooler temperatures than an engine mounted turbo system. Specifically, both the exhaust gases entering the turbocharger of the present invention and the compressed air charge exiting the turbocharger are cooler in temperature. The turbo system of the present invention produces its own xe2x80x9cintercooling effectxe2x80x9d by cooling down the already cooler than normal intake charge of air via heat dissipation produced by the extensive charge air duct surface area. Unlike a traditional intercooler, the turbo system of the present invention does not create a pressure differential to achieve the intercooling effect and thus does not require the turbocharger to increase boost pressure to compensate for the pressure drop across a conventional intercooler.
In addition, with the remote mounting of the turbocharger of the present invention, as for example under the vehicle where there is ample room, the expensive major modifications often necessary to create space under the hood in the engine compartment are significantly, if not totally, eliminated. Consequently, the elimination of these major modifications and added equipment under the hood dramatically lowers the cost of the installation and greatly reduces the costs of future maintenance and repair work required.
Moreover, remote mounting of the turbocharger of the present invention also has the result of a larger volume of engine oil. That is, engine oil contained in hoses, tubing, fittings and the pump provides additional oil to the oil system of the vehicle, reducing the frequency with which the engine oil has to pass through the turbocharger and engine components that primarily effect the lubricating capabilities of the oil. Moreover, the oil lines to and from the turbocharger function as engine oil coolers to lower the temperature of the engine oil, which in turn help to further cool the temperatures of the turbocharger, related components, and ultimately the intake air charge.
In one embodiment of the invention, a check valve is disposed between the engine oil source and the turbocharger near the turbocharger. The check valve creates a xe2x80x9cwetxe2x80x9d condition upon start up which allows rapid lubrication of the turbocharger upon engine start up.
In another embodiment, a pump controller is provided to help match the speed of the pump to the oil removal needs of the turbocharger. That is, as oil pressure within the system increases with increased engine rpm, more oil will enter the turbocharger. At lower engine rpms, the oil removal requirements for the pump are decreased with the decrease of oil pressure on the pressure side of the vehicle""s oiling system. Because a pump in accordance with the present invention may produce pump noise during operation, the controller can significantly reduce such pump noise when engine rpms are relatively low, and increase the pump speed as needed along with engine speed. Furthermore, the noise produced by the increased engine speed from the engine itself will help drown out or overcome the noise produced by the pump at such higher engine rpms.